The invention relates to a particle source in accordance with the introductory part of claim 1.
The PE-CVD technique is a plasma-chemical method for the coating of surfaces.
In contrast to conventional vacuum coating processes, sputtering and vapor-depositing, in the PE-CVD technique (plasma-enhanced chemical vapor deposition), the coating material is fed in gas form.
The gas molecules admitted into the vacuum chamber are ionized, dissociated and excited in a glow discharge by electron collision. The excited molecules and ions react at the substrate surfaces and deposit themselves thereon, forming a tight layer on the substrates.
In the field of CVD and etching technology, apparatus are generally known which operate with RF plasma excitation in parallel-plate reactors, in which, however, the energy of the particles striking the substrates cannot be adjusted independently of the plasma excitation.
In particular an apparatus is known (DE P 40 37 091.7) which uses for the production of plasmas microwaves which in combination with magnetic fields produce an electron-cyclotron resonance and thus produce an elevated ionization of atoms and molecules.
Also known is a particle source for a reactive ion beam etching or plasma depositing apparatus (DE 38 03 355) which has a container which envelops a gas or gas mixture provided for the plasma excitation, has an input for electromagnetic waves, preferably microwaves (.mu.W), supplying microwave energy to the gas or gas mixture, contains a first magnetic field generator that is oriented such that a magnetic field reaches into the interior of the container, and contains a second magnetic field generator which is disposed centrally to the first magnetic field generator.
The important disadvantages of RF plasma excitation in parallel-plate reactors are the strong coupling of plasma excitation and depositing or etching action (bias dependent on RF power) on the substrate, as well as the limitation of the substrate size by the uniformity of the RF excitation and of the gas dynamics.
For the above-named .mu.W plasma processes it is disadvantageous that they cannot be used in pass-through apparatus, and in static processes they are limited to round substrates of up to 200 mm diameter.